Generally, washing machines include a pulsator washing machine, a drum of which is vertically erected, a drum washing machine, a drum of which is horizontally laid, a washing machine having laundry washing and drying functions, and a drying machine having only a laundry drying machine.
The pulsator washing machine, the drum washing machine, and the washing machine having laundry washing and drying functions perform a washing operation using washing water.
Since a large amount of the washing water is required in the washing operation, an attempt for minimizing the amount of the washing water used has been developed.
For this reason, a steam generator is proposed. The steam generator serves to allow the washing operation to be performed using a small amount of washing water.
After the above conventional steam generator stores water supplied from a water pipe through a separate duct, a heater of the steam generator is operated only when steam supply is required.
The steam generated from the steam generator by the operation of the heater is supplied to a drum.
When the above-described steam generator is not used for a long period time, the water retained in the steam generator is stagnant or a lime component contained in the water is accumulated on the inner wall of the steam generator.
Particularly, the heater and a water level sensor are provided in the steam generator.
Accordingly, the lime component is accumulated on the surface of the heater or a power supply part for supplying power to the heater due to the water retained in the steam generator, thereby causing malfunction of the heater.
Further, the lime component is accumulated on terminals of the water level sensor due to the water retained in the steam generator, thereby causing malfunction of the water level sensor. The malfunction of the water level sensor causes the heater to be excessively operated, thus causing a danger of fire.